1. Field of the Invention
The present invention relates to a switch device of the type wherein a movable contact portion is connected to and disconnected from a fixed contact portion by the snap action of a movable member of a leaf spring structure.
2. Background Information
FIGS. 19 through 21 show a conventional switch device used in automobile window regulators.
In these drawings, 1 is a movable member of a leaf spring structure with a rectangular shape. Formed therein is a substantially rectangular slot 3 and a curved spring portion 2 extending downward. This movable member 1 has a movable contact 4 provided in its free end portion and a notch-like pivot portion 5 formed in its base end portion. Another notch-like pivot portion 6 is formed in a distal end portion of the spring portion 2. 7 is a switch casing on which a terminal board 10 is provided that has first and second support portions 8 and 9 spaced horizontally from each other. This switch casing 7 further has fixed contacts all and 12 spaced vertically from each other. The movable member 1 is accommodated in the casing 7 such that the pivot portion 5 of the base end portion is fitted in and supported by the first support portion 8 and the pivot portion 6 of the spring portion 2 by the second support portion 9.
In the state of FIG. 20, since the free end portion of the movable member 1 is applied with an obliquely-upward urging force from the spring force of the spring portion 2, the movable contact 4 is kept in contact with the fixed contact 11 on the closed side. As shown in FIG. 21, however, when the base end portion of the movable member 1 is depressed downward by a control member 13 so that arm portions 14 of the movable member 1 are moved downward beyond the pivot portion 6 of the spring portion 2, the free end portion of the movable member 1 is applied with an obliquely-downward urging force from the spring portion 2. Consequently, the free end portion of the movable member 1 is quickly moved downward by a downward component of the urging force, so that the movable contact 4 is disconnected from the fixed contact 11 on the normally closed side and brought into contact with the fixed contact 12 on the open side. Upon contact of the movable contact 4 with the fixed contact 12 on the open side, a window regulator motor is energized, so that a window is moved up or down.
In the foregoing structure of the prior art, to cause switching such that the movable contact 4 comes to contact with the fixed contact 12 on the open side, a portion of the movable member 1 corresponding to the second support portion 9 must be located below the pivot portion 6 of the spring portion 2 when the movable member 1 is depressed by the control member 13 in order to cause a snap action. Therefore, a slot 3 is needed in the movable member 1 since in the foregoing depressed state the second support portion 9 must penetrate through the movable member 1. With such a configuration, electric current for the motor of the window regulator flows through the arm portion 14 and spring portion 2 of the movable member 1. However, in order to increase the current capacity of the switch device, the width W of the movable member 1 must be increased in order to increase the width of the arm portion 14. Further, to increase the contact pressure of the movable contact 4 with respect to the fixed contacts 11 and 12, the width of the spring portion 2 must be increased, thus increasing the width W of the movable member 1. As a result, there is the problem of the overall size of the switch device becoming large.